In recent years, mixing faucets have to a large extent replaced the separate hot and cold water faucets which are used on sinks or lavatories. In mixing faucets, hot and cold water have been mixed to the desired ratio and delivered to the sink lavatory from a single spot at the desired temperature with the desired rate of flow. These faucets are usually provided with a single handle or lever which can be used to control both the desired rate of flow and the desired temperature of the water. In using mixing valves, the control handle is designed so that the fore-and-aft direction controls the rate of flow, and the side-to-side motion of the handle controls the temperature of the water. In traditional types of faucets, the lever is arranged so that a movement to the left causes hot water to flow while a movement to the right causes cold water to flow.
Mixing faucets are generally designed to incorporate a mixing valve which is contained in the form of a cartridge so that it may be removably attached to the manifold of the faucet housing within the decorative structure. Valve cartridges of this type include inlet openings for the entry of hot and cold water from the housing of the faucet, and an outlet opening through which the desired mixture of water may be returned from the valve cartridge to the faucet for discharge through a spout into the sink or lavatory. A stationary valve seat disc has been provided within the cartridge and includes ports corresponding to the openings in the housing. A movable valve plate disc is also provided and arranged for slidable sealing contact with the valve seat disc. The valve plate disc includes either a cavity in its surface adjacent to the valve seat disc, or ports therethrough which can be disposed to cooperate with corresponding ports in the valve seat disc to admit water from the hot and cold water lines for mixing purposes.
The movable valve plate disc is coupled to the control lever of the mixing faucet. The valve seat and plate discs are preferably constructed of a very hard ceramic material such as aluminum oxide, and their mating surfaces are polished extremely smooth and flat. These materials do not deteriorate appreciable with time, and are so hard that very little wear takes place even between their cooperating surfaces.
One of the problems of mixing faucets of this type has been their noisiness of operation due to cavitation occuring within the valve seat and plate discs. In order to reduce the noise problem, the cavity formed within the valve plate disc was provided with a series of ridges or terraces which were designed to break up, divide, and distribute the cavitation bubbles which are formed. However, these design improvements of the prior art managed to only reduce the noise level so that for some areas, it would not be objectionable. However, under certain plumbing codes, the cavitation noise produced within the valve plate disc and transmitted through the valve body and the feed pipes of the faucet was still found to be objectionable. In another embodiment of the prior art, a single layer screen was added across the ridges or terraced cavity of the valve plate disc to further break up the cavitation bubbles, responsible for the noise during the operation of the faucet. However, although the resultant noise was reduced, it was still found to objectionable under certain plumbing code standards.
Accordingly, it is an object of the present invention to provide a mixing faucet which is capable of reducing the noise level below mixing faucets of the prior art during operation.
It is a further object of the present invention to provide a mixing faucet which is capable of quiet operation to meet a larger number of plumbing code standards, and which is simple in design, easy to construct, and reliable in operation.